1. Field of the Invention
The invention relates to a vehicle control apparatus and method for controlling operation of a vehicle, more particularly, a hybrid vehicle combining an electric motor and an internal combustion engine.
2. Description of the Related Art
A so-called hybrid system in which an electric motor and an internal combustion engine as drive sources of a vehicle are combined is conventionally known. In the hybrid system, a control of stopping the driving of the engine under a predetermined condition in order to achieve improved fuel economy and reduced exhaust gas is sometimes performed. From such a situation where the engine is stopped, a control of restarting the driving of the engine under a predetermined condition is also performed.
For example, Japanese Patent Application Publication No. JP-A-11-348607 discloses a construction of an automatic stop-restart apparatus of automatically stopping and restarting an engine in a predetermined condition which comprises: wheel hold means for restraining rotation of a wheel of a vehicle during an automatic stop; and wheel hold continuation means for continuing maintenance of a braking force by the wheel hold means when the engine is restarted in a certain condition apart from a purpose of running the vehicle while the shift position of the transmission is a vehicle run position and the engine is at an automatic stop.
Furthermore, Japanese Patent Application Publication No. JP-A-2005-306374 discloses a construction of a vehicle control apparatus equipped with a drive source control device that automatically stops and restarts an engine, in which when the state of manipulation of a shift manipulation device is changed from a non-driving state to a driving state and a drive source is restarted, either the control of the braking force or the restart control of the drive source is performed on the basis of a result of comparison between the drive force of the engine and the braking force applied to the vehicle.
As described above, in some hybrid systems, when the shift position is not the vehicle run position, for example, is the parking position (hereinafter, referred to as “P position”), the engine is automatically stopped in order to reduce the fuel consumption and reduce the emission.
If during this state, electric components, such as, an air-conditioner, a stereo, etc., continue to be used, the state of charge of the battery declines; therefore, the engine is started in order to charge the battery. After this charging recovers the charged state of the battery, the engine is stopped again. Hence, the entire vehicle may vibrate in association with the starting and the stopping of the engine. In particular, when the vehicle is parked with the P position selected, it is often the case that the driver is not applying braking force to the vehicle, and therefore the vehicle is likely to vibrate at the time of starting or stopping the engine. Besides, since such vibration of the vehicle occurs not during running of the vehicle, but during a stop thereof, the vibration is likely to cause unpleasant feeling to occupants.
However, in the aforementioned related-art technologies, there is no consideration regarding the vibration of the vehicle caused when the engine is started with the shift position not being the vehicle run position but being the P position.